Cotinine [BSA]

Several studies have found aberrant DNA methylation levels in breast cancer cases, but factors influencing DNA methylation patterns and the mechanisms are not well understood. This case-control study evaluated blood methylation level of two repetitive elements and selected breast cancer-related genes in relation to breast cancer risk, and the associations with serum level of persistent organic pollutants (POPs) and breast cancer risk factors in Greenlandic Inuit. DNA methylation was determined using bisulphite pyrosequencing in blood from 74 breast cancer cases and 80 controls. Using first tertile as reference, the following was observed. Positive associations for ATM in second tertile (OR: 2.33, 95% CI: 1.04; 5.23) and ESR2 in third tertile (OR: 2.22, 95% CI: 0.97; 5.05) suggest an increased breast cancer risk with high DNA methylation. LINE-1 methylation was lower in cases than controls. In third tertile (OR: 0.42, 95% CI: 0.18; 0.98), associations suggest in accordance with the literature an increased risk of breast cancer with LINE-1 hypomethylation. Among controls, significant associations between methylation levels and serum level of POPs and breast cancer risk factors (age, body mass index, cotinine level) were found. Thus, breast cancer risk factors and POPs may alter the risk through changes in methylation levels; further studies are needed to elucidate the mechanisms.

Background: The relationship between self-reported and urinary cotinine-verified smoking status and atrial arrhythmia (AA) is unclear. The aim of this study was to evaluate the association of self-reported and urine cotinine-verified smoking status with AA. Method: A total of 201,788 participants (106,375 men, mean age 37 years) who had both a urinary cotinine measurement and electrocardiogram were included. Cotinine-verified current smoking was defined as a urinary cotinine level above 50 ng/mL. Individuals were divided into three groups based on self-reported smoking and two groups based on cotinineverified smoking status. Results: Among overall subjects, 505 had documented AA (0.3%) and 135 had atrial fibrillation (AF) (0.1%). Self-reported current smoking was associated with an increased risk of AA (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.06-1.91; P = 0.019) and AF (OR, 2.20; 95% CI, 1.24-3.90; P = 0.007), whereas self-reported former smoking had no significant association with AA (OR, 1.30; 95% CI, 0.97-1.73; P = 0.078) and AF (OR, 1.74; 95% CI, 1.00-3.04; P = 0.051). Cotinine-verified current smoking showed no significant association with AA (OR, 1.24; 95% CI, 0.98-1.58; P = 0.080) and AF (OR, 1.20; 95% CI, 0.79-1.83; P = 0.391). Conclusion: Self-reported current smoking was associated with AA and AF, while self reported former smoking and cotinine-verified current smoking showed no significant association with AA and AF.